1. Field of the Invention
The present invention relates generally to antimicrobial compositions for use on hard and soft surfaces. The invention also relates to cleaning compositions for use alone or with cleaning substrates. The composition also relates to natural cleaning compositions having a limited number of ingredients and having good cleaning properties and low residue.
2. Description of the Related Art
Silver ion based antimicrobial compositions are well-known but suffer from instability because silver ions are precipitated by a variety of anions at neutral pH, which severely limits the robustness of formulations containing surfactants and/or lower quality water because trace amounts of chloride ions in surfactants or water will readily cause precipitation of silver chloride, which causes formulation haziness and possible loss of antimicrobial activity.
To overcome this instability silver dihydrogen citrate has been developed as a “complexed” form of silver ion for example in U.S. Pat. No. 6,197,814 and U.S. Pat. App. 2006/0051430 to Arata. This complex is rather “weak”, and is generally restricted to low pH, for example around pH 2. To improve the antimicrobial efficacy U.S. Pat. App. 2005/0202066 to Arata adds an additional antimicrobial, such as a quaternary ammonium compound or an oxidizer to the composition. To promote greater stability at low pH, PCT App. WO 00/62618 to Batarseh et al. discloses silver ions chelated with amino acids, such as glutamic acid.
Prior art compositions do not combine effective soluble silver ion stability with rapid antimicrobial efficacy and the surface and personal safety advantages of use at higher pH levels. It is therefore an object of the present invention to provide an antimicrobial composition that overcomes the disadvantages and shortcomings associated with prior art antimicrobial compositions.